1. Field of the Invention
The present invention relates to an imaging apparatus including a display device capable of displaying an image of a target object to be imaged, and an image display method therefor.
2. Description of the Related Art
An imaging apparatus, such as a digital camera or a digital video camera, has a finder or a back surface provided with a display, such as a liquid crystal display or an organic EL display, which is used for imaging or confirmation of an image obtained by the imaging.
In general, in a case of displaying a moving image on the display, an afterimage remains when a light emission period ratio (duty cycle) of each frame or field is large, which causes such a “motion blur” that the contour of the moving image becomes obscure. The motion blur can be suppressed by reducing the light emission period ratio in accordance with a display speed of the moving image.
Japanese Patent Application Laid-Open No. 2006-323300 proposes a system in which the speed of a moving image is detected from input video data to control a value of the light emission period ratio for display. According to the technology disclosed in Japanese Patent Application Laid-Open No. 2006-323300, images are compared between frames, and the moving image speed is calculated to control the corresponding light emission period ratio, which can suppress the motion blur.
As described above, the display provided to the imaging apparatus, such as the digital camera or the digital video camera, is used when imaging is performed, and therefore has a display function called “live view” in which the image of a target object to be imaged is displayed instantaneously.
A live view function is used to determine a photographing composition or prepare for a photo opportunity while observing a displayed picture. Therefore, the display of the imaging apparatus needs to quickly display the moving image in order to allow a subject to be recognized.
Japanese Patent Application Laid-Open No. 2006-323300 discloses an improvement in moving image quality achieved by controlling the light emission period ratio based on the speed of the moving image obtained by analyzing a signal of a displayed image. However, the technology disclosed in Japanese Patent Application Laid-Open No. 2006-323300 is suitable for a display used to display content such as a TV monitor, but is not suitable for the display of the imaging apparatus due to poor responsiveness.
Further, the technology disclosed in Japanese Patent Application Laid-Open No. 2006-323300 compares the images between the frames in order to detect the moving image speed, which necessitates at least two frames to compare the images. Therefore, in the method of detecting the moving image speed, information on an image is sent to a display unit with a delay of at least a two-frame period. The display for the imaging apparatus needs to display an observed picture with high simultaneity, and the delay corresponding to multiple frames greatly affects usability.